1. Technical Field
The present invention relates to a microlens array, a method for manufacturing a microlens array, an electro-optical device, and an electronic apparatus.
2. Related Art
An electro-optical device is known which includes an electro-optical material, such as, a liquid crystal or the like, between an element substrate and a counter substrate. Examples of the electro-optical device include, for example, a liquid crystal device used as a liquid crystal light valve of a projector. There is demand for realizing a high optical utilization efficiency in such a liquid crystal device.
A liquid crystal device is provided with TFT elements that drive pixels, wirings and the like outside a pixel region on an element substrate, and a light blocking layer is provided so as to planarly overlap thereupon. Therefore, a portion of the incident light is blocked by the light blocking layer and not utilized. A configuration is known in which incident light is collected by the microlenses, thereby increasing the utilization efficiency of light, by including a microlens array in which microlenses are arranged on at least one of the element substrate and the counter substrate of a liquid crystal device.
JP-A-2011-158755 discloses a method for reducing the processing load when manufacturing the microlens array. In the configuration in JP-A-2011-158755, once a plurality of lenses is arranged in a pixel, and the size of the plurality of lenses is made a lens pitch of 1/integer, the center of each lens is biased in the center direction of the pixel by a fixed amount.
However, the microlens array disclosed in JP-A-2011-158755 has a problem of a poor utilization efficiency of light. Generally, because pixels are regularly (periodically) arranged in a liquid crystal device including a microlens array, the pixels become smaller as the liquid crystal device becomes increasingly high definition, and incident light is easily diffracted by the pixels. When strong diffracted light occurs, the solid angle of the luminous flux emitted from the liquid crystal device increases. When the liquid crystal device including such a microlens array is used as a liquid crystal light valve in a projector, the spread angle of light emitted from the liquid crystal device may exceed the incident angle that is stipulated by the F value of the projection lens. In this case, a portion of the light emitted from the liquid crystal device is not incident on the projection lens, and, as a result, the amount of light projected on the screen is lowered. Particularly, the problem is serious in the microlens array disclosed in JP-A-2011-158755, and even using a microlens array, there is a limit on the improvement in brightness. In other words, in a microlens array of the related art, a problem arises in that it is difficult to sufficiently improve the utilization efficiency of light.